Effects of host switching on gypsy moth (Lymantria dispar (L.)) under field conditions

Abstract

Effects of various single and two species diets on the performance of gypsy moth (Lymantria dispar (L.)) were studied when this insect was reared from hatch to population on intact host trees in the field. The tree species used for this study were red oak (Quercus rubra L.), white oak (Q. alba L.), bigtooth aspen (Populus grandidentata Michaux), and trembling aspen (P. tremuloides Michaux). These are commonly available host trees in the Lake States region. The study spanned two years and was performed at two different field sites in central Michigan. Conclusions drawn from this study include: (1) Large differences in gypsy moth growth and survival can occur even among diet sequences composed of favorable host species. (2) Larvae that spent their first two weeks feeding on red oak performed better during this time period than larvae on all other host species in terms of mean weight, mean relative growth rate (RGR), and mean level of larval development, while larvae on a first host of bigtooth aspen were ranked lowest in terms of mean weight, RGR, and level of larval development. (3) Combination diets do not seem to be inherently better or worse than diets composed of only a single species; rather, insect performance was affected by the types of host species eaten and the time during larval development that these host species were consumed instead of whether larvae ate single species diets or mixed species diets. (4) In diets composed of two host species, measures of gypsy moth performance are affected to different extents in the latter part of the season by the two different hosts; larval weights and development rates show continued effects of the first host fed upon while RGRs, mortality, and pupal weights are affected strongly by the second host type eaten. (5) Of the diets investigated in this study, early feeding on red oak followed by later feeding on an aspen, particularly trembling aspen, is most beneficial to insects in terms of attaining high levels of performance throughout their lives.

Census of the Bacterial Community of the Gypsy Moth Larval Midgut by Using Culturing and Culture-Independent Methods

“…The plants selected for this study represent a diversity of secondary plant metabolites that the gypsy moth commonly encounters in the field and may contribute to the observed differences in the midgut bacterial composition. In addition, individual gypsy moth larvae routinely switch host plants in the field with only minor direct effects on the larvae (69,70). However, host plant switching can alter the performance of gypsy moth parasitoids and could likewise affect the composition of the bacterial community (36).…”

Foliage‐age mixing within balsam fir increases the fitness of a generalist caterpillar

“…Both of these hypotheses have been used extensively to explain dietary mixing by generalist insects, many of which feed on a variety of plant species over the course of development (e.g. Kester & Smith, 1984;Barbosa et al, 1986;Bernays et al, 1994;Stoyenoff et al, 1994;van der Zee et al, 2002). Few studies of generalists, however, have considered the potential utility of dietary mixing for overcoming high levels of heterogeneity in foliage nutritional quality within individual hosts (but see Stockoff, 1993).…”

Macroalgal traits and the feeding and fitness of an herbivorous amphipod: the roles of selectivity, mixing, and compensation

“…Nutrition is a complex process, dependent not only on availability of nutrients, but also on nutrient balance. Thus, selective feeding on more nutritious plants, mixing foods to balance nutritional needs, switching plant hosts, and increasing consumption of lower quality foods (compensatory feeding) have all been proposed as important behaviors allowing herbivores to obtain adequate nourishment from low quality, or nutritionally unbalanced, plant food (Mattson 1980, Simpson & Simpson 1990, Pennings et al 1993, White 1993, Stoyenoff et al 1994, Stachowicz & Hay 1999, Cruz-Rivera & Hay 2000a, but see Bernays & Minkenberg 1997).…”

“…For example, predators may feed indiscriminately when prey are scarce, but may become more selective when particular prey are more abundant (Werner & Hall 1974, Stephens & Krebs 1986, Begon et al 1996. Similarly, herbivores may switch host plants during their development (Stoyenoff et al 1994), or may vary in their relative preference for different foods depending on geographic or temporal availability, and on herbivore feeding history (Fox & Morrow 1981, Strong et al 1984, Pennings et al 1993, Cronin & Hay 1996a, Bernays & Minkenberg 1997. Thus, an organism may feed selectively or be better able to mix specific diets when preferred foods are abundant, but become less discriminate or rely on compensatory feeding when preferred foods are scarce or when access to them is limited by biotic or abiotic factors (Stephens & Krebs 1986, Pennings et al 1993, Begon et al 1996, Cruz-Rivera & Hay 2000a.…”